blob: a112a4745d8b37919b6344c8dd336c500d84075a [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/fs/char_dev.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
Linus Torvalds1da177e2005-04-16 15:20:36 -07007#include <linux/init.h>
8#include <linux/fs.h>
Andrew Mortonb446b602007-02-20 13:57:48 -08009#include <linux/kdev_t.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070010#include <linux/slab.h>
11#include <linux/string.h>
12
13#include <linux/major.h>
14#include <linux/errno.h>
15#include <linux/module.h>
Joe Korty68eef3b2006-03-31 02:30:32 -080016#include <linux/seq_file.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070017
18#include <linux/kobject.h>
19#include <linux/kobj_map.h>
20#include <linux/cdev.h>
Jes Sorensen58383af2006-02-06 14:12:43 -080021#include <linux/mutex.h>
David Howells5da61852006-09-27 01:50:16 -070022#include <linux/backing-dev.h>
David Howells31d1d482010-08-06 16:34:43 +010023#include <linux/tty.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070024
David Howells07f3f052006-09-30 20:52:18 +020025#include "internal.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070026
27static struct kobj_map *cdev_map;
28
Jes Sorensen58383af2006-02-06 14:12:43 -080029static DEFINE_MUTEX(chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070030
31static struct char_device_struct {
32 struct char_device_struct *next;
33 unsigned int major;
34 unsigned int baseminor;
35 int minorct;
Neil Horman7170be52006-01-14 13:20:38 -080036 char name[64];
Linus Torvalds1da177e2005-04-16 15:20:36 -070037 struct cdev *cdev; /* will die */
Joe Korty68eef3b2006-03-31 02:30:32 -080038} *chrdevs[CHRDEV_MAJOR_HASH_SIZE];
Linus Torvalds1da177e2005-04-16 15:20:36 -070039
40/* index in the above */
Yang Zhange61eb2e2010-12-17 09:00:18 +010041static inline int major_to_index(unsigned major)
Linus Torvalds1da177e2005-04-16 15:20:36 -070042{
Joe Korty68eef3b2006-03-31 02:30:32 -080043 return major % CHRDEV_MAJOR_HASH_SIZE;
Linus Torvalds1da177e2005-04-16 15:20:36 -070044}
45
Joe Korty68eef3b2006-03-31 02:30:32 -080046#ifdef CONFIG_PROC_FS
Neil Horman7170be52006-01-14 13:20:38 -080047
Joe Korty68eef3b2006-03-31 02:30:32 -080048void chrdev_show(struct seq_file *f, off_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -070049{
50 struct char_device_struct *cd;
Linus Torvalds1da177e2005-04-16 15:20:36 -070051
Joe Korty68eef3b2006-03-31 02:30:32 -080052 if (offset < CHRDEV_MAJOR_HASH_SIZE) {
53 mutex_lock(&chrdevs_lock);
54 for (cd = chrdevs[offset]; cd; cd = cd->next)
55 seq_printf(f, "%3d %s\n", cd->major, cd->name);
56 mutex_unlock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070057 }
Neil Horman7170be52006-01-14 13:20:38 -080058}
59
Joe Korty68eef3b2006-03-31 02:30:32 -080060#endif /* CONFIG_PROC_FS */
Linus Torvalds1da177e2005-04-16 15:20:36 -070061
62/*
63 * Register a single major with a specified minor range.
64 *
65 * If major == 0 this functions will dynamically allocate a major and return
66 * its number.
67 *
68 * If major > 0 this function will attempt to reserve the passed range of
69 * minors and will return zero on success.
70 *
71 * Returns a -ve errno on failure.
72 */
73static struct char_device_struct *
74__register_chrdev_region(unsigned int major, unsigned int baseminor,
75 int minorct, const char *name)
76{
77 struct char_device_struct *cd, **cp;
78 int ret = 0;
79 int i;
80
Oliver Neukum11b0b5a2006-03-25 03:08:13 -080081 cd = kzalloc(sizeof(struct char_device_struct), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -070082 if (cd == NULL)
83 return ERR_PTR(-ENOMEM);
84
Jes Sorensen58383af2006-02-06 14:12:43 -080085 mutex_lock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070086
87 /* temporary */
88 if (major == 0) {
89 for (i = ARRAY_SIZE(chrdevs)-1; i > 0; i--) {
90 if (chrdevs[i] == NULL)
91 break;
92 }
93
Linus Walleij49db08c2016-02-19 15:36:07 +010094 if (i < CHRDEV_MAJOR_DYN_END)
Fengguang Wu077e2642016-07-12 15:05:49 +080095 pr_warn("CHRDEV \"%s\" major number %d goes below the dynamic allocation range\n",
Linus Walleij49db08c2016-02-19 15:36:07 +010096 name, i);
97
Linus Torvalds1da177e2005-04-16 15:20:36 -070098 if (i == 0) {
99 ret = -EBUSY;
100 goto out;
101 }
102 major = i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103 }
104
105 cd->major = major;
106 cd->baseminor = baseminor;
107 cd->minorct = minorct;
Cyrill Gorcunov8c401882009-01-06 14:41:08 -0800108 strlcpy(cd->name, name, sizeof(cd->name));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700109
110 i = major_to_index(major);
111
112 for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
113 if ((*cp)->major > major ||
Amos Waterland01d553d2006-09-29 02:00:08 -0700114 ((*cp)->major == major &&
115 (((*cp)->baseminor >= baseminor) ||
116 ((*cp)->baseminor + (*cp)->minorct > baseminor))))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117 break;
Amos Waterland01d553d2006-09-29 02:00:08 -0700118
119 /* Check for overlapping minor ranges. */
120 if (*cp && (*cp)->major == major) {
121 int old_min = (*cp)->baseminor;
122 int old_max = (*cp)->baseminor + (*cp)->minorct - 1;
123 int new_min = baseminor;
124 int new_max = baseminor + minorct - 1;
125
126 /* New driver overlaps from the left. */
127 if (new_max >= old_min && new_max <= old_max) {
128 ret = -EBUSY;
129 goto out;
130 }
131
132 /* New driver overlaps from the right. */
133 if (new_min <= old_max && new_min >= old_min) {
134 ret = -EBUSY;
135 goto out;
136 }
Chengguang Xubb22efc2019-02-15 20:27:11 +0800137
138 if (new_min < old_min && new_max > old_max) {
139 ret = -EBUSY;
140 goto out;
141 }
142
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143 }
Amos Waterland01d553d2006-09-29 02:00:08 -0700144
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145 cd->next = *cp;
146 *cp = cd;
Jes Sorensen58383af2006-02-06 14:12:43 -0800147 mutex_unlock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700148 return cd;
149out:
Jes Sorensen58383af2006-02-06 14:12:43 -0800150 mutex_unlock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700151 kfree(cd);
152 return ERR_PTR(ret);
153}
154
155static struct char_device_struct *
156__unregister_chrdev_region(unsigned major, unsigned baseminor, int minorct)
157{
158 struct char_device_struct *cd = NULL, **cp;
159 int i = major_to_index(major);
160
Jes Sorensen58383af2006-02-06 14:12:43 -0800161 mutex_lock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162 for (cp = &chrdevs[i]; *cp; cp = &(*cp)->next)
163 if ((*cp)->major == major &&
164 (*cp)->baseminor == baseminor &&
165 (*cp)->minorct == minorct)
166 break;
167 if (*cp) {
168 cd = *cp;
169 *cp = cd->next;
170 }
Jes Sorensen58383af2006-02-06 14:12:43 -0800171 mutex_unlock(&chrdevs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172 return cd;
173}
174
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700175/**
176 * register_chrdev_region() - register a range of device numbers
177 * @from: the first in the desired range of device numbers; must include
178 * the major number.
179 * @count: the number of consecutive device numbers required
180 * @name: the name of the device or driver.
181 *
182 * Return value is zero on success, a negative error code on failure.
183 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184int register_chrdev_region(dev_t from, unsigned count, const char *name)
185{
186 struct char_device_struct *cd;
187 dev_t to = from + count;
188 dev_t n, next;
189
190 for (n = from; n < to; n = next) {
191 next = MKDEV(MAJOR(n)+1, 0);
192 if (next > to)
193 next = to;
194 cd = __register_chrdev_region(MAJOR(n), MINOR(n),
195 next - n, name);
196 if (IS_ERR(cd))
197 goto fail;
198 }
199 return 0;
200fail:
201 to = n;
202 for (n = from; n < to; n = next) {
203 next = MKDEV(MAJOR(n)+1, 0);
204 kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
205 }
206 return PTR_ERR(cd);
207}
208
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700209/**
210 * alloc_chrdev_region() - register a range of char device numbers
211 * @dev: output parameter for first assigned number
212 * @baseminor: first of the requested range of minor numbers
213 * @count: the number of minor numbers required
214 * @name: the name of the associated device or driver
215 *
216 * Allocates a range of char device numbers. The major number will be
217 * chosen dynamically, and returned (along with the first minor number)
218 * in @dev. Returns zero or a negative error code.
219 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700220int alloc_chrdev_region(dev_t *dev, unsigned baseminor, unsigned count,
221 const char *name)
222{
223 struct char_device_struct *cd;
224 cd = __register_chrdev_region(0, baseminor, count, name);
225 if (IS_ERR(cd))
226 return PTR_ERR(cd);
227 *dev = MKDEV(cd->major, cd->baseminor);
228 return 0;
229}
230
Rolf Eike Beerd247e2c2006-07-14 00:24:23 -0700231/**
Tejun Heo1905b1b2009-08-06 18:13:23 +0900232 * __register_chrdev() - create and register a cdev occupying a range of minors
Rolf Eike Beerd247e2c2006-07-14 00:24:23 -0700233 * @major: major device number or 0 for dynamic allocation
Tejun Heo1905b1b2009-08-06 18:13:23 +0900234 * @baseminor: first of the requested range of minor numbers
235 * @count: the number of minor numbers required
Rolf Eike Beerd247e2c2006-07-14 00:24:23 -0700236 * @name: name of this range of devices
237 * @fops: file operations associated with this devices
238 *
239 * If @major == 0 this functions will dynamically allocate a major and return
240 * its number.
241 *
242 * If @major > 0 this function will attempt to reserve a device with the given
243 * major number and will return zero on success.
244 *
245 * Returns a -ve errno on failure.
246 *
247 * The name of this device has nothing to do with the name of the device in
248 * /dev. It only helps to keep track of the different owners of devices. If
249 * your module name has only one type of devices it's ok to use e.g. the name
250 * of the module here.
Rolf Eike Beerd247e2c2006-07-14 00:24:23 -0700251 */
Tejun Heo1905b1b2009-08-06 18:13:23 +0900252int __register_chrdev(unsigned int major, unsigned int baseminor,
253 unsigned int count, const char *name,
254 const struct file_operations *fops)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700255{
256 struct char_device_struct *cd;
257 struct cdev *cdev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258 int err = -ENOMEM;
259
Tejun Heo1905b1b2009-08-06 18:13:23 +0900260 cd = __register_chrdev_region(major, baseminor, count, name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700261 if (IS_ERR(cd))
262 return PTR_ERR(cd);
Greg Kroah-Hartman1ff97642011-12-13 11:06:49 -0800263
Linus Torvalds1da177e2005-04-16 15:20:36 -0700264 cdev = cdev_alloc();
265 if (!cdev)
266 goto out2;
267
268 cdev->owner = fops->owner;
269 cdev->ops = fops;
270 kobject_set_name(&cdev->kobj, "%s", name);
Greg Kroah-Hartman1ff97642011-12-13 11:06:49 -0800271
Tejun Heo1905b1b2009-08-06 18:13:23 +0900272 err = cdev_add(cdev, MKDEV(cd->major, baseminor), count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273 if (err)
274 goto out;
275
276 cd->cdev = cdev;
277
278 return major ? 0 : cd->major;
279out:
280 kobject_put(&cdev->kobj);
281out2:
Tejun Heo1905b1b2009-08-06 18:13:23 +0900282 kfree(__unregister_chrdev_region(cd->major, baseminor, count));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283 return err;
284}
285
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700286/**
Partha Pratim Mukherjee594069b2015-07-27 16:15:19 -0700287 * unregister_chrdev_region() - unregister a range of device numbers
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700288 * @from: the first in the range of numbers to unregister
289 * @count: the number of device numbers to unregister
290 *
291 * This function will unregister a range of @count device numbers,
292 * starting with @from. The caller should normally be the one who
293 * allocated those numbers in the first place...
294 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700295void unregister_chrdev_region(dev_t from, unsigned count)
296{
297 dev_t to = from + count;
298 dev_t n, next;
299
300 for (n = from; n < to; n = next) {
301 next = MKDEV(MAJOR(n)+1, 0);
302 if (next > to)
303 next = to;
304 kfree(__unregister_chrdev_region(MAJOR(n), MINOR(n), next - n));
305 }
306}
307
Tejun Heo1905b1b2009-08-06 18:13:23 +0900308/**
309 * __unregister_chrdev - unregister and destroy a cdev
310 * @major: major device number
311 * @baseminor: first of the range of minor numbers
312 * @count: the number of minor numbers this cdev is occupying
313 * @name: name of this range of devices
314 *
315 * Unregister and destroy the cdev occupying the region described by
316 * @major, @baseminor and @count. This function undoes what
317 * __register_chrdev() did.
318 */
319void __unregister_chrdev(unsigned int major, unsigned int baseminor,
320 unsigned int count, const char *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700321{
322 struct char_device_struct *cd;
Tejun Heo1905b1b2009-08-06 18:13:23 +0900323
324 cd = __unregister_chrdev_region(major, baseminor, count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700325 if (cd && cd->cdev)
326 cdev_del(cd->cdev);
327 kfree(cd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700328}
329
330static DEFINE_SPINLOCK(cdev_lock);
331
332static struct kobject *cdev_get(struct cdev *p)
333{
334 struct module *owner = p->owner;
335 struct kobject *kobj;
336
337 if (owner && !try_module_get(owner))
338 return NULL;
339 kobj = kobject_get(&p->kobj);
340 if (!kobj)
341 module_put(owner);
342 return kobj;
343}
344
345void cdev_put(struct cdev *p)
346{
347 if (p) {
Brian King7da68442005-07-12 13:58:30 -0700348 struct module *owner = p->owner;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349 kobject_put(&p->kobj);
Brian King7da68442005-07-12 13:58:30 -0700350 module_put(owner);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351 }
352}
353
354/*
355 * Called every time a character special file is opened
356 */
Denis Cheng922f9cf2008-02-08 04:22:00 -0800357static int chrdev_open(struct inode *inode, struct file *filp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700358{
Al Viroe84f9e52013-09-22 14:17:15 -0400359 const struct file_operations *fops;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700360 struct cdev *p;
361 struct cdev *new = NULL;
362 int ret = 0;
363
364 spin_lock(&cdev_lock);
365 p = inode->i_cdev;
366 if (!p) {
367 struct kobject *kobj;
368 int idx;
369 spin_unlock(&cdev_lock);
370 kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx);
371 if (!kobj)
372 return -ENXIO;
373 new = container_of(kobj, struct cdev, kobj);
374 spin_lock(&cdev_lock);
Jonathan Corbeta30427d2008-05-18 15:39:11 -0600375 /* Check i_cdev again in case somebody beat us to it while
376 we dropped the lock. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700377 p = inode->i_cdev;
378 if (!p) {
379 inode->i_cdev = p = new;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700380 list_add(&inode->i_devices, &p->list);
381 new = NULL;
382 } else if (!cdev_get(p))
383 ret = -ENXIO;
384 } else if (!cdev_get(p))
385 ret = -ENXIO;
386 spin_unlock(&cdev_lock);
387 cdev_put(new);
388 if (ret)
389 return ret;
Christoph Hellwiga518ab92008-08-11 15:34:22 +0200390
391 ret = -ENXIO;
Al Viroe84f9e52013-09-22 14:17:15 -0400392 fops = fops_get(p->ops);
393 if (!fops)
Christoph Hellwiga518ab92008-08-11 15:34:22 +0200394 goto out_cdev_put;
395
Al Viroe84f9e52013-09-22 14:17:15 -0400396 replace_fops(filp, fops);
Christoph Hellwiga518ab92008-08-11 15:34:22 +0200397 if (filp->f_op->open) {
Greg Kroah-Hartman1ff97642011-12-13 11:06:49 -0800398 ret = filp->f_op->open(inode, filp);
Christoph Hellwiga518ab92008-08-11 15:34:22 +0200399 if (ret)
400 goto out_cdev_put;
401 }
402
403 return 0;
404
405 out_cdev_put:
406 cdev_put(p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700407 return ret;
408}
409
410void cd_forget(struct inode *inode)
411{
412 spin_lock(&cdev_lock);
413 list_del_init(&inode->i_devices);
414 inode->i_cdev = NULL;
Dan Williams3bc52c42016-07-24 21:55:45 -0700415 inode->i_mapping = &inode->i_data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416 spin_unlock(&cdev_lock);
417}
418
Adrian Bunk75c96f82005-05-05 16:16:09 -0700419static void cdev_purge(struct cdev *cdev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700420{
421 spin_lock(&cdev_lock);
422 while (!list_empty(&cdev->list)) {
423 struct inode *inode;
424 inode = container_of(cdev->list.next, struct inode, i_devices);
425 list_del_init(&inode->i_devices);
426 inode->i_cdev = NULL;
427 }
428 spin_unlock(&cdev_lock);
429}
430
431/*
432 * Dummy default file-operations: the only thing this does
433 * is contain the open that then fills in the correct operations
434 * depending on the special file...
435 */
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -0800436const struct file_operations def_chr_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700437 .open = chrdev_open,
Arnd Bergmann6038f372010-08-15 18:52:59 +0200438 .llseek = noop_llseek,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700439};
440
441static struct kobject *exact_match(dev_t dev, int *part, void *data)
442{
443 struct cdev *p = data;
444 return &p->kobj;
445}
446
447static int exact_lock(dev_t dev, void *data)
448{
449 struct cdev *p = data;
450 return cdev_get(p) ? 0 : -1;
451}
452
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700453/**
454 * cdev_add() - add a char device to the system
455 * @p: the cdev structure for the device
456 * @dev: the first device number for which this device is responsible
457 * @count: the number of consecutive minor numbers corresponding to this
458 * device
459 *
460 * cdev_add() adds the device represented by @p to the system, making it
461 * live immediately. A negative error code is returned on failure.
462 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700463int cdev_add(struct cdev *p, dev_t dev, unsigned count)
464{
Dmitry Torokhov2f0157f2012-10-21 17:57:19 -0700465 int error;
466
Linus Torvalds1da177e2005-04-16 15:20:36 -0700467 p->dev = dev;
468 p->count = count;
Dmitry Torokhov2f0157f2012-10-21 17:57:19 -0700469
470 error = kobj_map(cdev_map, dev, count, NULL,
471 exact_match, exact_lock, p);
472 if (error)
473 return error;
474
475 kobject_get(p->kobj.parent);
476
477 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700478}
479
480static void cdev_unmap(dev_t dev, unsigned count)
481{
482 kobj_unmap(cdev_map, dev, count);
483}
484
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700485/**
486 * cdev_del() - remove a cdev from the system
487 * @p: the cdev structure to be removed
488 *
489 * cdev_del() removes @p from the system, possibly freeing the structure
490 * itself.
491 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700492void cdev_del(struct cdev *p)
493{
494 cdev_unmap(p->dev, p->count);
495 kobject_put(&p->kobj);
496}
497
498
499static void cdev_default_release(struct kobject *kobj)
500{
501 struct cdev *p = container_of(kobj, struct cdev, kobj);
Dmitry Torokhov2f0157f2012-10-21 17:57:19 -0700502 struct kobject *parent = kobj->parent;
503
Linus Torvalds1da177e2005-04-16 15:20:36 -0700504 cdev_purge(p);
Dmitry Torokhov2f0157f2012-10-21 17:57:19 -0700505 kobject_put(parent);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700506}
507
508static void cdev_dynamic_release(struct kobject *kobj)
509{
510 struct cdev *p = container_of(kobj, struct cdev, kobj);
Dmitry Torokhov2f0157f2012-10-21 17:57:19 -0700511 struct kobject *parent = kobj->parent;
512
Linus Torvalds1da177e2005-04-16 15:20:36 -0700513 cdev_purge(p);
514 kfree(p);
Dmitry Torokhov2f0157f2012-10-21 17:57:19 -0700515 kobject_put(parent);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516}
517
518static struct kobj_type ktype_cdev_default = {
519 .release = cdev_default_release,
520};
521
522static struct kobj_type ktype_cdev_dynamic = {
523 .release = cdev_dynamic_release,
524};
525
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700526/**
527 * cdev_alloc() - allocate a cdev structure
528 *
529 * Allocates and returns a cdev structure, or NULL on failure.
530 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700531struct cdev *cdev_alloc(void)
532{
Oliver Neukum11b0b5a2006-03-25 03:08:13 -0800533 struct cdev *p = kzalloc(sizeof(struct cdev), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700534 if (p) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700535 INIT_LIST_HEAD(&p->list);
Greg Kroah-Hartmanf9cb0742007-12-17 23:05:35 -0700536 kobject_init(&p->kobj, &ktype_cdev_dynamic);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700537 }
538 return p;
539}
540
Jonathan Corbetcf3e43d2006-09-29 02:00:44 -0700541/**
542 * cdev_init() - initialize a cdev structure
543 * @cdev: the structure to initialize
544 * @fops: the file_operations for this device
545 *
546 * Initializes @cdev, remembering @fops, making it ready to add to the
547 * system with cdev_add().
548 */
Arjan van de Ven99ac48f2006-03-28 01:56:41 -0800549void cdev_init(struct cdev *cdev, const struct file_operations *fops)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700550{
551 memset(cdev, 0, sizeof *cdev);
552 INIT_LIST_HEAD(&cdev->list);
Greg Kroah-Hartmanf9cb0742007-12-17 23:05:35 -0700553 kobject_init(&cdev->kobj, &ktype_cdev_default);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700554 cdev->ops = fops;
555}
556
557static struct kobject *base_probe(dev_t dev, int *part, void *data)
558{
559 if (request_module("char-major-%d-%d", MAJOR(dev), MINOR(dev)) > 0)
560 /* Make old-style 2.4 aliases work */
561 request_module("char-major-%d", MAJOR(dev));
562 return NULL;
563}
564
565void __init chrdev_init(void)
566{
567 cdev_map = kobj_map_init(base_probe, &chrdevs_lock);
568}
569
570
571/* Let modules do char dev stuff */
572EXPORT_SYMBOL(register_chrdev_region);
573EXPORT_SYMBOL(unregister_chrdev_region);
574EXPORT_SYMBOL(alloc_chrdev_region);
575EXPORT_SYMBOL(cdev_init);
576EXPORT_SYMBOL(cdev_alloc);
577EXPORT_SYMBOL(cdev_del);
578EXPORT_SYMBOL(cdev_add);
Tejun Heo1905b1b2009-08-06 18:13:23 +0900579EXPORT_SYMBOL(__register_chrdev);
580EXPORT_SYMBOL(__unregister_chrdev);